1. Field of the Invention.
The present invention relates to treating drilling mud and more particularly to an apparatus and method for removing solids from drilling mud.
In rotary well drilling it has been common practice to supplement ordinary muds by drilling mud additives. These additives are in a fine state of subdivision and include colloidal material and mud weighting material for enhancing the suspension of drilled solids in the mud as well as increasing the weight per unit of measure of mud. The drilling mud additives form a desirable thin filter cake or seal on the borehole wall. Drilled native solids in drilling mud are progressively subdivided until they reach a comminuted state. A concentration of such finely divided native solids in the mud results in an undesirable substantial increase in the mud viscosity tending to form a gel. In prior years excess drilling mud, containing a concentration of drilled solids, was deposited in a reservoir pit, adjacent the well site.
Drilling mud additives are relatively expensive and the mud mixture may be continuously reused if excess solids are removed. For ecology and economic reasons the reserve pit disposal of drilling muds has been discontinued. Furthermore, space requirements of off shore drilling rig platforms does not permit the use of reserve pits.
In off shore drilling operations it has been the practice to transport the drilling mud, containing a concentration of drilled solids, to the shore for disposal. The disposal of such drilling mud presents a problem for the reason the colloidal material in the muds delays evaporation of the contained water and thus a compacting of the solids. Drilling mud additives and water contained in the mud removed from off shore drilling locations for disposal must be replaced by fresh water and additives from shore.
This invention overcomes the above problems by providing an apparatus and method for removal of excess drilled solids from a drilling mud stream.
2. Description of the Prior Art
The prior art generally discloses apparatus for removing drilling mud solids which, in addition to conventional apparatus for removing relatively large drill cuttings, such as a shale shaker, generally comprise a series of tanks or receptacles forming a passageway for the mud in which the flow rate is reduced in each successive tank for permitting a settling action of the solids. The only similarity between this invention and such prior apparatus is that the mud flow rate is reduced to a rate below its normal rate of flow through a conduit, or the like, but this invention does not rely on a settling of the solids. The solids being removed by an electrolytic action.